Recording media storing digital data of music contents, video data and others are available in various types including magnetic disk, optical disk, and magneto-optical disk. A semiconductor memory card is one of such recording media, and it mainly uses a semiconductor memory such as flash ROM as a storage device, and can be reduced in size of the recording medium, and it has been widely used in a digital still camera, a mobile telephone terminal, and other small portable appliances.
As an example of such a semiconductor memory card, there is a semiconductor memory card having a copyright protection function capable of storing digital copyright object (see, for example, patent document 1). The semiconductor memory card has, in order to protect the copyright of the digital copyright object, an authentication area for allowing access to an external device only when authentication is successful in the external device in the semiconductor memory, and a non-authentication area for allowing access regardless of the result of authentication.
On the other hand, data stored in the semiconductor memory card is managed by a file system, and the user can easily handle the stored data as a file. File systems known hitherto include FAT file system (see non-patent document 1). The FAT system is a file system generally used in personal computers and other information appliances, and is characterized by uniform management of storage position of the data composing a file by a table which is called FAT (File Allocation Table). When data stored in the semiconductor memory card is managed by FAT file system, a device which can interpret the FAT file system can access the data stored in the semiconductor memory card, and data can be exchanged between such devices by way of the semiconductor memory card.
Aside from the FAT file system, file systems also include UDF file system (Universal Disk Format) (see non-patent document 2), and NTFS file system (New Technology File System), if types of file systems that can be interpreted by devices are different, data cannot be exchanged among such devices by way of the semiconductor memory card.
To solve this problem, hitherto, it has been proposed to use an information recording medium which sets an area for storing plural sets of file system management information, and an area for storing common file data (see, for example, patent document 2). In this conventional method, after the information recording medium is loaded in the device, a desired file system is selected, and the area storing file system management information corresponding to the selected file system is accessed with the beginning address as address 0 to read out the file system management information. Thus, by selecting and using any one of the plurality pieces of file system management information, data can be exchanged with a common information recording medium between the devices which interprets different file systems.
Patent document 1: JP-A-2003-233795.
Patent document 2: JP-A-8-272541.
Non-patent document 1: ISO/IEC9293, “Information Technology—Volume and file structure of disk cartridges for information,” 1994
Non-patent document 2: “Optical Storage Technology Association (Universal Disk Format Specification Revision 1.50)”, 1997.